pscl (version 0.5)

summary.zeroinfl: Summarizing Zero-Inflated Regression Models for Count Data

Description

summary method for class "zeroinfl"

Usage

## S3 method for class 'zeroinfl':
summary(object, ...)
  ## S3 method for class 'summary.zeroinfl':
print(x,
                                   digits = max(3, getOption("digits") - 3),
                                   ...)

Arguments

object

an object of class "zeroinfl", usually a result of a call to zeroinfl

x

an object of class "summary.zeroinfl", usually a result of a call to summary.zeroinfl

digits

the number of significant digits to use when printing

...

further arguments passed to or from other methods

Value

• The function summary.zeroinfl computes and returns a list of summary statistics from the zero-inflated regression model, including
• coefficents
  a matrix, with columns for the MLEs, their standard errors, $z$-statistic, and corresponding (two-sided) $p$-value.
• vc
  The estimated variance-covariance matrix of the MLEs
• beta
  The MLEs from the count component of the model
• gamma
  The MLEs from the zero-inflated component of the model
• theta
  If a zero-inflated negative binomial model is fit, the MLE of the over-dispersion parameter
• llh
  The value of the log-likelihood function at the MLEs

Keyword

methods

Details

print.summary.zeroinfl tries to be smart about formatting the display of the MLEs, standard errors, etc, essentially using the same code as appears in link{print.summary.lm}

See Also

zeroinfl, predict.zeroinfl

Methods are supplied for the generic functions link{coef} and link{logLik}, for objects of class "zeroinfl".

Examples

data(bioChemists)
zip <- zeroinfl(count=art ~ .,
                x = ~ fem + mar + kid5 + phd + ment,
                z = ~ fem + mar + kid5 + phd + ment,
                data=bioChemists,trace=TRUE)
summary(zip)
coef(zip)
logLik(zip)